Compound, organic thin film, photoelectric conversion element, imaging element, optical sensor, and solid-state imaging device

Abstract

The following formula (1): [Formula 1] TIFF0007593538000024.tif73170 (X is an oxygen atom or NR6, and R1 to R6 are each independently a hydrogen atom, a halogen atom, a cyano group, a linear, branched or cyclic alkyl group, an aryl group, or the like.) A compound represented by the formula:

Description

[Technical field]

[0001] The present disclosure relates to a compound, an organic thin film, a photoelectric conversion element, an imaging element, an optical sensor, and a solid-state imaging device. [Background technology]

[0002] Conventionally, a technology for photoelectrically converting visible light into an electric signal has been known and is used, for example, in an image sensor. Such an image sensor is provided in a solid-state image sensor such as a charge coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor. In recent years, the pixel size of solid-state image sensors has been reduced, and organic photoelectric conversion films have been studied to accommodate this. For example, Patent Document 1 and Patent Document 2 disclose an organic photoelectric conversion film composed of a subphthalocyanine and an imide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-32754 A [Patent Document 2] Special Publication No. 2018-512423 [Patent Document 3] Special Publication No. 2014-506736 Summary of the Invention [Problem to be solved by the invention]

[0004] A solid-state imaging device is required to have both high spectral selectivity and a high S / N ratio. Therefore, it is desired that the solid-state imaging device has a high external quantum efficiency (EQE) and low dark current characteristics. To achieve such compatibility, a method is known in which an electron transport layer and a hole blocking layer, and / or a hole transport layer and an electron blocking layer are disposed between a photoelectric conversion unit and an electrode unit. Here, the electron transport layer, the hole blocking layer, the electron blocking layer, and the like, which are widely used in the field of organic electronic devices, are disposed at the interface between an electrode or a conductive film and other films in a film constituting a device. These layers play a role of controlling the reverse movement of holes or electrons, respectively, to adjust the leakage of unnecessary holes or electrons. For example, Patent Document 3 shows an example in which 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA) is used as a material for such a layer.

[0005] However, conventional hole blocking layers and electron blocking layers, including those disclosed in Patent Document 3, have room for further improvement in terms of suppressing leakage current in the dark.

[0006] The present invention aims to provide a novel compound that can suppress leakage current in the dark and is particularly useful as a photoelectric conversion element material, a photoelectric conversion element material, and an organic thin film, a photoelectric conversion element, an imaging element, a photosensor, and a solid-state imaging device that each contain the compound. [Means for solving the problem]

[0007] The present invention is as follows. [1] The following formula (1): [ka] (X is an oxygen atom or NR6, R1, R2, R3, R4, R5 and R6 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, a carboalkoxy group, a carboaryloxy group, an acyl group, and a monovalent heterocyclic group, and any adjacent R1, R2, R3, R4, R5 and R6 may be a part of a fused aliphatic ring or a fused aromatic ring. Two R1, R2, R3, R4, R5 and X may be the same or different from each other. The fused aliphatic ring and the fused aromatic ring may contain one or more atoms other than carbon.) A compound represented by the formula: [2] The compound represented by formula (1) has an energy level of the lowest unoccupied molecular orbital, determined by density functional theory, of -6.00 eV or more and -3.40 eV or less. [3] The compound represented by formula (1) above, wherein the difference between the energy level of the lowest unoccupied molecular orbital and the energy level of the highest occupied molecular orbital, as determined by density functional theory, is 3.00 eV or more and 4.00 eV or less. [4] The compound described above is a material for a photoelectric conversion element. [5] An organic thin film comprising the compound described above. [6] The organic thin film described above has a maximum absorption wavelength of 450 nm or less in its light absorption band. [7] A photoelectric conversion element including a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film, A photoelectric conversion element, wherein the photoelectric conversion film contains the above-mentioned material for photoelectric conversion elements. [8] A photoelectric conversion element including a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film, A photoelectric conversion element, wherein the photoelectric conversion film comprises the organic thin film described above. [9] The photoelectric conversion film includes a photoelectric conversion layer and an auxiliary layer, The photoelectric conversion element according to any one of the above, wherein the auxiliary layer is made of only the organic thin film, or made of a plurality of films including the organic thin film.

[10] An imaging element comprising the above photoelectric conversion element.

[11] The imaging element described above, which is formed by stacking two or more of the photoelectric conversion elements.

[12] An imaging element is formed by arranging a plurality of the above photoelectric conversion elements in an array.

[13] An optical sensor comprising the above-mentioned imaging element.

[14] A solid-state imaging device comprising the imaging element described above. Effect of the Invention

[0008] According to the present invention, it is possible to provide a novel compound that is particularly useful as a photoelectric conversion element material, a photoelectric conversion element material, and an organic thin film, a photoelectric conversion element, an imaging element, an optical sensor, and a solid-state imaging device each containing the compound. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view partially illustrating an example of a photoelectric conversion element of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a form for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to the present embodiment described below. The present invention can be modified in various ways without departing from the gist of the invention. In addition, the same elements in the drawings will be given the same reference numerals, and duplicated explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0011] (compound) The compound of the present embodiment is represented by the following formula (1): [ka] (Hereinafter, this compound will also be referred to as "compound (1).") In this case, X is an oxygen atom or NR6, and R1, R2, R3, R4, R5, and R6 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, an optionally substituted linear, branched, or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an aryl ... R1, R2, R3, R4, R5 and R6 are selected from the group consisting of koxy, acylamino, acyloxy, aryl, carboxamido, carboalkoxy, carboaryloxy, acyl and monovalent heterocyclic groups, and any adjacent R1, R2, R3, R4, R5 and R6 may be part of a condensed aliphatic ring or a condensed aromatic ring. Two R1, R2, R3, R4, R5 and X may be the same or different from each other. The condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.

[0012] Such a compound (1) can suppress the leakage current in the dark, and shows excellent properties especially as a photoelectric conversion element material. Although the reason is not clear, the present inventors consider it as follows. However, the reason is not limited to the following. That is, the compound (1) has two aryloxy groups in the molecular structure, and the two aryloxy groups are located diagonally to the naphthyl group, so that the energy level of the lowest unoccupied molecular orbital of the compound (1) is lowered, and the leakage current in the dark can be suppressed. In addition, since the compound (1) has two aryloxy groups, the crystallinity is low and it is easy to have a plurality of stable structures with close energy levels, so that it is difficult to obtain a highly regular molecular arrangement as a solid. This makes it possible to suppress the occurrence of film thickness disturbance and electrical short circuit (pinhole) that may occur due to partial aggregation in the thin film. Furthermore, the compound (1) has a low molecular orientation in the layer direction in the thin film compared to when it does not have two aryloxy groups, so that high electron transport properties are obtained, and excellent properties as a photoelectric conversion element material are obtained.

[0013] Examples of halogen atoms include a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br) and an iodine atom (I).

[0014] The linear alkyl group may be a linear alkyl group having 1 to 12 carbon atoms, such as methyl (Me), ethyl (Et), n-propyl (n-Pr), n-butyl (n-Bu), n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and n-dodecyl. Among these, from the viewpoint of more effectively and reliably exerting the effects of the present invention, a linear alkyl group having 1 to 3 carbon atoms is preferred, a methyl group or an ethyl group is more preferred, and a methyl group is even more preferred.

[0015] The branched alkyl group may be a branched alkyl group having 1 to 12 carbon atoms in the alkyl group, and examples thereof include isopropyl group (i-Pr), sec-butyl group (s-Bu), tert-butyl group (t-Bu), isopentyl group, sec-pentyl group, 3-pentyl group, neopentyl group, isohexyl group, isooctyl group, isononyl group, isodecyl group, and isododecyl group. The linear or branched alkyl group may have a substituent. Examples of the substituent include halogen atoms such as fluorine atoms, monovalent groups having an aromatic ring such as benzyl group, naphthyl group, and phenoxy group, monovalent groups having a heteroatom such as alkoxy groups, aminoalkyl groups, and thioalkyl groups, monovalent groups having a heterocycle such as pyridyl group, hydroxyl group, carboxyl group, amino group, and thiol group.

[0016] The cyclic alkyl group may be a cyclic alkyl group having 3 to 10 carbon atoms in the alkyl group, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. The cyclic alkyl group may have a heteroatom such as a nitrogen atom, an oxygen atom, and a sulfur atom in the ring. Examples of such a cyclic alkyl group include a pyrrolidinyl group, an oxazolidinyl group, a pyrazolidinyl group, a thiazolidinyl group, an imidazolidinyl group, a dioxofuranyl group, a tetrahydrofuranyl group, a tetrahydrothiophenyl group, a piperazinyl group, a dioxanyl group, and a morpholinyl group. Furthermore, a monovalent group such as a hydroxyl group, a carboxyl group, an amino group, and a thiol group may be bonded to the cyclic alkyl group.

[0017] The thioalkyl group (-SR; hereinafter, R represents an alkyl group) and the thioaryl group (-SAr; hereinafter, Ar represents an aryl group) may be a thioalkyl group having 1 to 12 carbon atoms in the alkyl group and a thioaryl group having 6 to 16 carbon atoms in the aryl group. The thioalkyl group and the thioaryl group may further have a substituent such as an amino group, a hydroxy group, a halogen atom, an alkoxy group, or a thioalkyl group. Examples of such thioalkyl group and thioaryl group include a methylthio group, an ethylthio group, a phenylthio group, a toluylthio group, an aminophenylthio group, a hydroxyphenylthio group, a fluorophenylthio group, a dimethylphenylthio group, and a methylthiophenylthio group.

[0018] The arylsulfonyl group (-SO2-Ar) may be an arylsulfonyl group having 6 to 16 carbon atoms in the aryl group, and examples thereof include a phenylsulfonyl group, a toluenesulfonyl group, a dimethylbenzenesulfonyl group, a mesitylenesulfonyl group, an octylbenzenesulfonyl group, and a naphthalenesulfonyl group.

[0019] The aryloxy group (-O-Ar) may be an aryloxy group having 6 to 16 carbon atoms in the aryl group. The aryloxy group may further have a substituent such as a cyano group, a halogen atom such as a fluorine atom, a hydroxy group, an alkoxy group such as a methoxy group, an amino group, an alkylamino group, a thiol group, or an aryloxy group. Examples of such an aryloxy group include a phenoxy group, a cyanophenoxy group, a methylcyanophenoxy group, a dimethylcyanophenoxy group, a fluorocyanophenoxy group, a dicyanophenoxy group, a methoxycyanophenoxy group, a tricyanophenoxy group, a cyanonaphthoxy group, a dicyanonaphthoxy group, a 2-methylphenoxy group, a 3-methylphenoxy group, a 4-methylphenoxy group, a fluoromethylphenoxy group, a dimethylphenoxy group, a 3-hydroxyphenoxy group, Examples of such groups include a fluoro-3-hydroxyphenoxy group, a 2-hydroxyphenoxy group, a fluoro-2-hydroxyphenoxy group, a methoxyphenoxy group, an ethoxyphenoxy group, a fluorophenoxy group, a perfluorophenoxy group, a dimethoxyphenoxy group, an aminophenoxy group, an N,N-dimethylaminophenoxy group, a thiophenoxy group, a (trifluoromethyl)phenoxy group, a naphthoxy group, a methoxynaphthoxy group, a fluoronaphthoxy group, and a phenoxyphenoxy group.

[0020] The alkylsulfonyl group (-SO2-R) may be an alkylsulfonyl group in which the alkyl group has 1 to 12 carbon atoms, and examples thereof include a mesyl group, an ethylsulfonyl group, and an n-butylsulfonyl group.

[0021] The alkylamino group (here, the alkylamino group is -NHR or -NR2, and the two Rs may be the same or different) may be an alkylamino group in which the alkyl group has 1 to 12 carbon atoms, and examples thereof include a methylamino group, an ethylamino group, a n-propylamino group, a n-butylamino group, a n-pentylamino group, a n-hexylamino group, a n-heptylamino group, a n-octylamino group, a n-nonylamino group, a n-decylamino group, a n-dodecylamino group, an isopropylamino group, a sec-butylamino group, a tert-butylamino group, an isopentylamino group, a sec-pentylamino group, a 3-pentylamino group, a neopentylamino group, an isohexylamino group, an isoheptylamino group, an isooctylamino group, an isononylamino group, an isodecylamino group, an isododecylamino group, a dimethylamino group, a diethylamino group, a diisopropylamino group, and an isopropylethylamino group.

[0022] The arylamino group (here, the arylamino group is -NHAr or -NAr2, and the two Ar may be the same or different) may be an arylamino group having 6 to 16 carbon atoms in the aryl group, and examples thereof include an anilyl group, a toluidinyl group, a dimethylanilyl group, an isopropylanilyl group, a t-butylanilyl group, a fluoroanilyl group, a trifluoromethylanilyl group, a bis(trifluoromethyl)anilyl group, a pyridylamino group, a methylpyridylamino group, a fluoropyridylamino group, a pyrimidylamino group, and a biphenylamino group.

[0023] The alkoxy group (-OR) may be an alkoxy group having 1 to 12 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an n-butyloxy group, an n-pentoxy group, an n-hexoxy group, an n-heptoxy group, an n-octoxy group, an n-nonoxy group, an n-decoxy group, an n-dodecoxy group, an isopropoxy group, a sec-butyloxy group, a tert-butyloxy group, an isopentoxy group, a sec-pentoxy group, a 3-pentoxy group, a neopentoxy group, an isohexoxy group, an isooctoxy group, an isonoxy group, an isodecoxy group, and an isododecoxy group.

[0024] The acylamino group (-NH-COR or -NH-COAr) may have 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group, and may have a substituent such as a halogen atom such as a fluorine atom, an alkoxy group, or a cyano group. Examples of such acylamino groups include an acetylamino group, a propionylamino group, a benzoylamino group, a methylbenzoylamino group, a dimethylbenzoylamino group, a methoxybenzoylamino group, a cyanobenzoylamino group, and a bis(trifluoromethyl)benzoylamino group.

[0025] The acyloxy group (-O-COR or -O-COAr) may have 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group. The acyloxy group may further have a halogen atom such as a fluorine atom and a substituent such as a cyano group, and may have a heteroatom such as a nitrogen atom in the aromatic ring. Examples of such an acyloxy group include a benzoyloxy group, a toluoyloxy group, a dimethylbenzoyloxy group, a cyanobenzoyloxy group, a fluorobenzoyloxy group, a bis(trifluoromethyl)benzoyloxy group, a pyridine carboxy group, and a methylpyridine carboxy group.

[0026] The aryl group (-Ar) may be an aryl group having 6 to 16 carbon atoms. The aryl group may further have a substituent such as an amino group, a hydroxy group, a thiol group, a halogen atom such as a fluorine atom, a nitro group, or a cyano group, and may have a heteroatom such as a nitrogen atom in the aromatic ring. Examples of such aryl groups include a phenyl group, a methylphenyl group, an ethylphenyl group, a dimethylphenyl group, a trimethylphenyl group, a methoxyphenyl group, a dimethoxyphenyl group, a trimethoxyphenyl group, a methoxymethylphenyl group, an aminophenyl group, a diaminophenyl group, an aminomethylphenyl group, a hydroxyphenyl group, a dihydroxyphenyl group, a hydroxymethylphenyl group, a hydroxyethylphenyl group, a thiophenyl group, a methylthiophenyl group, a dithiophenyl group, a fluorophenyl group, a fluoromethylphenyl group, a trifluoromethylphenyl group, a perfluorophenyl group, a fluoro(trifluoromethyl)phenyl group, a bis(trifluoromethyl)phenyl group, a cyanophenyl group, a methylcyanophenyl group, a dimethylcyanophenyl group, a dicyanophenyl group, a methoxycyanophenyl group, a tricyanophenyl group, and a dicyanophenyl group. , a methylcyanopyridyl group, a (trifluoromethyl)cyanopyridyl group, a dimethylcyanopyridyl group, a dicyanopyridyl group, a methoxycyanopyridyl group, a tricyanopyridyl group, a cyanopyridyl group, a naphthyl group, a nitrophenyl group, a dinitrophenyl group, a nitrofluorophenyl group, a methylnaphthyl group, an ethylnaphthyl group, a dimethylnaphthyl group, a trimethylnaphthyl group, a methoxynaphthyl group, a dimethoxynaphthyl group, a trimethoxynaphthyl group, an aminonaphthyl group, a diaminonaphthyl group, an aminomethylnaphthyl group, a hydroxynaphthyl group, a dihydroxynaphthyl group, a hydroxymethylnaphthyl group, a hydroxyethylnaphthyl group, a thionaphthyl group, a methylthionaphthyl group, a dithionaphthyl group, a fluoronaphthyl group, a trifluoromethylnaphthyl group, a perfluoronaphthyl group, a di(trifluoromethyl)naphthyl group, a biphenyl group, and a cyanobiphenyl group.

[0027] The carboxyamide group (here, the carboxyamide group is -CO-NH2, -CO-NHR, -CONR2, where the two Rs may be the same or different, or -CONHAr, or -CONAr2, where the two Ars may be the same or different) may be a carboxyamide group in which the alkyl group has 1 to 12 carbon atoms or the aryl group has 6 to 16 carbon atoms, and examples thereof include a dimethylcarboxyamide group and a diphenylcarboxyamide group.

[0028] The carboalkoxy group and carboaryloxy group (-COOR or -COOAr) may be a carboalkoxy group having 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group, and examples thereof include a carbomethoxy group and a carbophenoxy group.

[0029] The monovalent heterocyclic group may be a monovalent heterocyclic group having 3 to 14 carbon atoms, and examples thereof include a furanyl group, a thienyl group, a pyrrolyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, a dioxazolyl group, an isoxazolyl group, an oxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, a triazolyl group, an indolyl group, an indolinyl group, an indolizinyl group, an indazolinyl group, an indoleninyl group, a benzofuranyl group, a benzothienyl group, a carbazolyl group, and a dibenzofuranyl group. , dibenzothienyl group, pyridinyl group, diazinyl group, oxazinyl group, thiazinyl group, dioxinyl group, dithienyl group, triazinyl group, pyrimidinyl group, pyrazinyl group, pyridazinyl group, quinolinyl group, isoquinolinyl group, cinnonyl group, phthalazinyl group, quinazolinyl group, naphthyridinyl group, purinyl group, pteridinyl group, acridinyl group, phenanthridinyl group, phenanthrolinyl group, xanthenyl group, phenoxazinyl group, thianthrenyl group, morpholinyl group, and phenazinyl group.

[0030] In the compound (1) of this embodiment, although not particularly limited, R1, R2, R3, R4 and R5 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxy group, a nitro group, and an optionally substituted linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, a carboalkoxy group, a carboaryloxy group, an acyl group, and a monovalent heterocyclic group, more preferably selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group, and an optionally substituted linear, branched or cyclic alkyl group, even more preferably selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group, an unsubstituted alkyl group, and an alkyl group substituted with a halogen atom, particularly preferably selected from the group consisting of a cyano group and an unsubstituted alkyl group, and extremely preferably a cyano group. When compound (1) has the above-mentioned structure, leakage current in the dark can be further suppressed.

[0031] In this embodiment, R1, R2, R3, R4 and R5 may be the same or different. From the viewpoint of more effectively and reliably exerting the action and effect of the present invention, although not particularly limited, it is preferable that at least two selected from R1, R2, R3, R4 and R5 are the same, and it is more preferable that at least four selected from R1, R2, R3, R4 and R5 are the same. In addition, the two R1, R2, R3, R4 and R5 in compound (1) may be the same or different, and it is preferable that they are the same.

[0032] The compound (1) of this embodiment is not particularly limited, but from the viewpoint of more effectively and reliably exerting the effects of the present invention, it is preferable that at least one of R1, R2, R3, R4 and R5 is not a hydrogen atom, and it is more preferable that at least one of R1, R2, R3, R4 and R5 is selected from the group consisting of a halogen atom, a nitro group, a cyano group, and a linear, branched or cyclic alkyl group which may be substituted. Furthermore, it is more preferable that at least one of R1, R2, R3, R4 and R5 is selected from the group consisting of a halogen atom, a nitro group, a cyano group, an unsubstituted alkyl group and an alkyl group substituted with a halogen atom, it is particularly preferable that at least one of R1, R2, R3, R4 and R5 is selected from the group consisting of a cyano group and an unsubstituted alkyl group, and it is extremely preferable that at least one of R1, R2, R3, R4 and R5 is a cyano group.

[0033] Compound (1) of the present embodiment is not particularly limited, but from the viewpoint of more effectively and reliably exerting the effects of the present invention, it is preferable that at least two of R1, R2, R3, R4, and R5 are hydrogen atoms, it is more preferable that at least two or at least three of R1, R2, R3, R4, and R5 are hydrogen atoms, and it is particularly preferable that at least four of R1, R2, R3, R4, and R5 are hydrogen atoms.

[0034] In this embodiment, when at least four of R1, R2, R3, R4, and R5 are hydrogen atoms, it is preferable that R2, R3, R4, and R5 are hydrogen atoms, from the viewpoint of more effectively and reliably achieving the effects of the present invention, although there is no particular limitation.

[0035] In addition, when R2, R3, R4, and R5 are hydrogen atoms, R1 is preferably selected from the group consisting of a halogen atom, a hydroxy group, a thiol group, an amino group, a cyano group, a carboxy group, a nitro group, and an optionally substituted linear, branched, or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, a carboalkoxy group, a carboaryloxy group, an acyl group, and a monovalent heterocyclic group, more preferably selected from the group consisting of a halogen atom, a nitro group, a cyano group, and an optionally substituted linear, branched, or cyclic alkyl group, even more preferably selected from the group consisting of a halogen atom, a nitro group, a cyano group, an unsubstituted alkyl group, and an alkyl group substituted with a halogen atom, particularly preferably selected from the group consisting of a cyano group and an unsubstituted alkyl group, and extremely preferably a cyano group.

[0036] In the compound (1) of the present embodiment, X is an oxygen atom or NR6, and the two Xs may be the same or different from each other. From the viewpoint of more effectively and reliably exerting the effects of the present invention, it is preferable that the two Xs are the same. When X is NR6, it is not particularly limited, but R6 is preferably selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, and a linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxyamide group, a carboalkoxy group, a carboaryloxy group, an acyl group, and a monovalent heterocyclic group, which may be substituted, more preferably selected from the group consisting of a linear, branched or cyclic alkyl group, an aryl group, and a monovalent heterocyclic group, which may be substituted, and particularly preferably an aryl group which may be substituted with a group selected from the group consisting of a halogen atom, a nitro group, a cyano group, and an alkyl group substituted with a halogen atom. By having the above-mentioned structure of compound (1), the leakage current in the dark can be further suppressed. In addition, when both of the two Xs in compound (1) are NR6, from the viewpoint of more effectively and reliably achieving the effects of the present invention, the two R6s may be the same or different, and are preferably the same.

[0037] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the energy level of the lowest unoccupied molecular orbital (LUMO) of the compound (1) of this embodiment obtained by the density functional theory is preferably -6.00 eV or more and -3.40 eV or less, more preferably -5.50 eV or more and -3.45 eV or less. The energy level may be -6.00 eV or more and -3.80 eV or less, or may be -5.50 eV or more and -3.80 eV or less. The compound (1) of this embodiment can be subjected to structural optimization by molecular simulation using the density functional theory (for example, molecular simulation using the quantum chemistry calculation program Gaussian manufactured by Gaussian) to obtain the energy level of the lowest unoccupied molecular orbital of the compound (1). The energy level of the lowest unoccupied molecular orbital of the compound (1) of this embodiment obtained by the density functional theory may be adjusted by changing R1 to R6. From the viewpoint of setting the energy level of the lowest unoccupied molecular orbital within the above range, it is preferable that at least one of R1, R2, R3, R4, and R5 is an electron-withdrawing group, and R6 is preferably an aryl group substituted with an electron-withdrawing group.

[0038] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the energy level of the highest occupied molecular orbital (HOMO) of the compound (1) of this embodiment obtained by the density functional theory is preferably -8.00 eV or more and -6.00 eV or less, and more preferably -7.90 eV or more and -6.10 eV or less. The energy level of the highest occupied molecular orbital of the compound (1) of this embodiment can be obtained by performing structural optimization by molecular simulation using the density functional theory (for example, molecular simulation using the quantum chemical calculation program Gaussian manufactured by Gaussian) using the density functional theory. In addition, the energy level of the highest occupied molecular orbital of the compound (1) of this embodiment obtained by the density functional theory is not particularly limited, but may be adjusted by changing R1 to R6. From the viewpoint of setting the energy level of the highest occupied molecular orbital within the above range, it is preferable that at least one of R1, R2, R3, R4, and R5 is an electron-withdrawing group, and R6 is preferably an aryl group substituted with an electron-withdrawing group.

[0039] The difference (eV) between the energy level of the lowest unoccupied molecular orbital and the energy level of the highest occupied molecular orbital ([energy level of the highest occupied molecular orbital]-[energy level of the lowest unoccupied molecular orbital]) of the compound (1) of this embodiment obtained by density functional theory is preferably 3.00 eV or more and 4.00 eV or less. By keeping the difference in energy levels within the above range, leakage current in the dark tends to be reduced when used as a photoelectric conversion element material.

[0040] The molecular weight of the compound (1) of this embodiment is preferably 400 or more, more preferably 430 or more, and even more preferably 450 or more. When the molecular weight is 400 or more, the change in physical properties caused by the thermal motion of molecules that may occur during the heating operation in the manufacturing process of the organic thin film using the compound (1) or in a high-temperature use environment can be further suppressed. In particular, when the compound (1) is formed by vacuum deposition, the molecular weight of the compound (1) is preferably 1000 or less, more preferably 950 or less, and even more preferably 900 or less. When the molecular weight is 1000 or less, the thermal energy required for sublimation when forming the organic thin film of the compound (1) by vacuum deposition can be further reduced. As a result, the compound (1) does not deteriorate due to heat, and a good thin film can be formed. However, when forming a thin film by solution coating, such a problem is unlikely to occur, so the molecular weight of the compound (1) may be greater than 1000.

[0041] The compound (1) of this embodiment preferably has a temperature at which the weight ratio of the weight loss caused by heating under an inert gas atmosphere is within 5% of the weight before heating (hereinafter, sometimes referred to as the "5% weight loss temperature") of 200°C or higher, more preferably 250°C or higher. When the 5% weight loss temperature is 200°C or higher, changes in physical properties due to the thermal motion of molecules that may occur during heating operations in the manufacturing process of an organic thin film using the compound (1) or in a high-temperature usage environment can be further suppressed. The 5% weight loss temperature can be measured by differential thermal analysis.

[0042] The compound (1) of this embodiment is obtained by, for example, synthesis as described below. In the product (100 mass%) obtained by synthesis, the content of compound (1) is preferably 90 mass% or more, more preferably 93 mass% or more, and even more preferably 97 mass% or more. When the content of compound (1) is 90 mass% or more, it is possible to more effectively and reliably avoid carrier trapping at impurity levels caused by unintended impurities when compound (1) is used in a photoelectric conversion element. As a result, carrier recombination is suppressed, and a photoelectric conversion element having better performance can be obtained. The content can be measured by liquid chromatography, gas chromatography, elemental analysis, or the like, but any known method may be used.

[0043] In the compound (1) of this embodiment, when both or either one of the two X's is NR6, preferred combinations of R1, R2, R3, R4, R5, and R6 are shown below. However, the compound (1) is not limited thereto. [ka] [ka] [ka] [ka] [ka] [ka]

[0044] [ka]

[0045] In the compound (1) of this embodiment, when X is an oxygen atom, preferred combinations of R1, R2, R3, R4, and R5 are shown below, however, the compound (1) is not limited thereto. [ka]

[0046] Specific examples of compound (1) are shown below, however, compound (1) is not limited to these. [ka] [ka]

[0047] [ka] [ka]

[0048] The compound (1) of this embodiment is represented by the following formula: [ka] It is particularly preferable that the compound is represented by the formula: Since such a compound has four cyano groups, it can suppress leakage current in the dark, and it exhibits excellent properties as a photoelectric conversion element material. The reason for this is considered to be as follows. In such a compound, the energy level of the lowest unoccupied molecular orbital is lowered and the energy level of the highest occupied molecular orbital is also lowered, and it has a high energy gap while maintaining a low energy level of the lowest unoccupied molecular orbital. As a result, it is considered that the above compound can suppress leakage current in the dark and can obtain excellent properties as a photoelectric conversion element material. However, the reason is not limited to this.

[0049] Compound (1) can be synthesized, for example, according to the following scheme. [ka]

[0050] More specifically, for example, a compound (1) in which X is an oxygen atom can be obtained by a side chain addition reaction from a commercially available compound (α). In addition, a compound (1) in which X is NR6 can be obtained by further performing an imide reaction. Alternatively, a compound (1) in which X is NR6 can be obtained by performing a side chain addition reaction via an intermediate in which a commercially available compound (α) is imidized. In addition, by adjusting the equivalent amount of the reagent in the imide reaction, a compound in which one of the two Xs in formula (1) is an oxygen atom and the other is NR6 can be obtained. More specifically, the imidization can be synthesized by the method described in, for example, Organic Electronics, 63, 250 (2018). In addition, a side chain addition reaction may be performed using a compound in which R1 to R5 are introduced, or R1 to R5 may be introduced after the side chain addition reaction. The side chain addition reaction can be carried out by a coupling reaction or the method described in Asian Journal of Organic Chemistry, 2, 779 (2013).

[0051] (Photoelectric conversion element materials) The compound (1) of this embodiment is used as a photoelectric conversion element material. More specifically, it is used as a material contained in each layer of the photoelectric conversion element described later. Among them, from the viewpoint of more effectively and reliably exhibiting the effects of the present invention, the compound (1) is preferably contained in the auxiliary layer, and more preferably contained in at least one of the electron transport layer and the hole blocking layer.

[0052] In addition, the compound (1) of this embodiment can be used as a photosensitive material as it is, or can be mixed with other materials to be used as a photosensitive composition. The content of the compound (1) in the photosensitive composition may be 50% by mass or more based on the total amount of the composition. The content may be 95% by mass or less, 90% by mass or less, or 80% by mass or less. Materials other than the compound (1) in the photosensitive composition are not particularly limited as long as they are contained in ordinary photosensitive compositions. Examples of such materials include n-type semiconductor materials, p-type semiconductor materials, and light-absorbing materials described later. These are used alone or in combination of two or more.

[0053] (organic thin film) The organic thin film of this embodiment includes the compound (1) of this embodiment or the above-mentioned photoelectric conversion element material. Such an organic thin film can be prepared by a general dry film formation method or wet film formation method. Specifically, examples of the organic thin film include vacuum processes such as resistance heating deposition, electron beam deposition, sputtering, and molecular lamination methods, solution processes such as casting, spin coating, dip coating, blade coating, wire bar coating, and spray coating, printing methods such as inkjet printing, screen printing, offset printing, and relief printing, and soft lithography methods such as microcontact printing. In general, it is desirable that the photoelectric conversion element material can be used in a process in which the compound is applied in a solution state from the viewpoint of ease of processing. However, in the case of a photoelectric conversion element in which organic thin films are laminated, a dry film formation method such as resistance heating deposition is preferable because the coating solution may damage the underlying film.

[0054] For example, in the dry film formation method, the photoelectric conversion element material of this embodiment and, if necessary, other materials according to the application of the photoelectric conversion element are mixed to form a composition, and the composition is evaporated onto a substrate or other film under vacuum to obtain an organic thin film. In addition, in the wet film formation method, the photoelectric conversion element of this embodiment and, if necessary, other materials according to the application of the photoelectric conversion element are mixed with a solvent to form a liquid composition, which is coated and printed on a substrate or other film, and further dried to obtain an organic thin film.

[0055] The organic thin film of this embodiment may contain a material other than compound (1) which is a material for photoelectric conversion devices of this embodiment. The content of compound (1) in the organic thin film of this embodiment is not particularly limited as long as the performance required for use as a material for photoelectric conversion devices is exhibited. For example, the content of compound (1) may be 50% by mass or more with respect to the total amount of the organic thin film, but from the viewpoint of more effectively and reliably achieving the effects of the present invention, it is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The upper limit of the content of compound (1) may be 100% by mass. When the organic thin film of this embodiment contains a material other than compound (1), the material is not particularly limited as long as it is used as a material for ordinary photoelectric conversion devices. Examples of such materials include n-type semiconductor materials, p-type semiconductor materials, and light absorbing materials described later, as well as molybdenum oxide, alkali metals, and alkali metal compounds called doping materials. These are used alone or in combination of two or more.

[0056] The thickness of the organic thin film cannot be limited because it depends on the resistance value and charge mobility of each substance, but is usually 0.5 nm to 5000 nm, may be 1 nm to 1000 nm, or may be 5 nm to 500 nm.

[0057] In order to more effectively and reliably achieve the effects of the present invention, the organic thin film of this embodiment preferably has a maximum absorption wavelength in the light absorption band of 450 nm or less.

[0058] (Photoelectric conversion element) The photoelectric conversion element of this embodiment generates electric charges according to the amount of incident light, and outputs the generated electric charges to the outside of the photoelectric conversion element via a capacitor (hereinafter also referred to as the "storage section") for storing the generated electric charges, a transistor circuit (hereinafter also referred to as the "readout section") for reading the electric charges, and the like. Here, the photoelectric conversion element refers to a photoelectric conversion film that absorbs at least a portion of incident light disposed between a pair of opposing electrodes, and light is incident on the photoelectric conversion element from above the electrodes. The photoelectric conversion film is a photosensitive thin film that contains a material that absorbs at least a portion of incident light in the infrared range, and generates holes and electrons as a result of the incidence of light. The photoelectric conversion element of this embodiment may also have a photoelectric conversion element (hereinafter also referred to as an "infrared photoelectric conversion element") that generates charges according to the amount of incident light in the infrared range, where the infrared photoelectric conversion element is a photoelectric conversion film (hereinafter also referred to as an "infrared photoelectric conversion film") that absorbs infrared light arranged between a pair of opposing electrodes, and light is incident on the infrared photoelectric conversion element from above the electrodes. The infrared photoelectric conversion film is a photosensitive thin film that contains a material (hereinafter also referred to as an "infrared absorbing material") that absorbs at least a portion of incident light in the infrared range, and generates holes and electrons as a result of the incidence of light.

[0059] The photoelectric conversion element of this embodiment will be described with appropriate reference to Fig. 1. The photoelectric conversion element 100 includes a lower electrode 102 which is a first electrode film, an upper electrode 106 which is a second electrode film, and a photoelectric conversion film 110 located between the lower electrode 102 and the upper electrode 106. The photoelectric conversion element 100 may include a substrate 101, which is usually insulating, on the opposite side of the upper electrode 106 to the photoelectric conversion film 110.

[0060] When the photoelectric conversion film 110 has hole transport properties or electron transport properties, the lower electrode 102 and the upper electrode 106 play a role of extracting holes from the photoelectric conversion film 110 and collecting them, or extracting electrons and discharging them. Materials that can be used as these electrodes are not particularly limited as long as they have a certain degree of conductivity, but it is preferable to select them in consideration of adhesion to the adjacent photoelectric conversion film 110, electron affinity, ionization potential, stability, etc. Examples of materials that can be used as electrodes include conductive metal oxides such as tin oxide (NESA), indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel, and tungsten; inorganic conductive substances such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole, and polyaniline; and carbon. These materials may be used alone or in combination.

[0061] The lower electrode 102, which is the first electrode film, is made of a conductive film having optical transparency, for example, made of indium tin oxide (ITO). The material constituting the lower electrode 102 is not limited to ITO, and examples thereof include tin oxide (SnO2)-based materials to which a dopant is added, and zinc oxide-based materials to which a dopant is added to zinc oxide (ZnO). Examples of zinc oxide-based materials include aluminum zinc oxide (AZO) to which aluminum (Al) is added as a dopant, gallium zinc oxide (GZO) to which gallium (Ga) is added, and indium zinc oxide (IZO) to which indium (In) is added. Alternatively, examples of the material constituting the lower electrode 102 include CuI, InSbO4, ZnMgO, CuInO2, MgIN2O4, CdO, and ZnSnO3. The thickness of the lower electrode 102 is, for example, 5 nm or more and 3000 nm or less, and may be 5 nm or more and 500 nm or less, or may be 10 nm or more and 300 nm or less.

[0062] The upper electrode 106, which is the second electrode film, may be made of a conductive film having the same light transparency as the lower electrode 102, or may be made of a metal such as aluminum that is usually used for electrodes of photoelectric conversion elements. In addition, in a solid-state imaging device using a solid-state imaging element as one pixel, the upper electrode 106 may be separated for each pixel, or may be formed as an electrode common to each pixel. The thickness of the upper electrode 106 is, for example, 5 nm to 3000 nm, may be 5 nm to 500 nm, or may be 10 nm to 300 nm.

[0063] The conductivity of the material used for the electrodes such as the first electrode film and the second electrode film is not particularly limited as long as it does not unnecessarily hinder the light reception of the photoelectric conversion element, but it is preferable that the conductivity is as high as possible from the viewpoint of the signal strength and power consumption of the photoelectric conversion element. For example, as a transparent electrode, an ITO film having a conductivity of 300Ω / □ or less functions sufficiently as an electrode. However, commercially available products of substrates having an ITO film with a conductivity of about several Ω / □ (for example, 5 to 9Ω / □) are also available, and a substrate with such high conductivity is preferable.

[0064] When an ITO film is used, the thickness of the electrode can be selected arbitrarily in consideration of the electrical conductivity, but is usually 5 nm to 3000 nm, preferably 10 nm to 300 nm. Methods for forming a film such as ITO include the conventionally known deposition method, electron beam method, sputtering method, chemical reaction method, and coating method. The ITO film provided on the substrate may be subjected to UV-ozone treatment or plasma treatment as necessary.

[0065] In addition, when stacking multiple photoelectric conversion films with different wavelengths to be detected, the electrode film used between each photoelectric conversion film needs to transmit light of wavelengths other than the light detected by each photoelectric conversion film. From this perspective, it is preferable to use a material that transmits 90% or more of the incident light for the electrode film, and it is more preferable to use a material that transmits 95% or more of the light. The electrode film is an electrode film other than the pair of electrodes mentioned above.

[0066] Furthermore, when a visible photoelectric conversion section that senses infrared light or light in a different visible light range is further provided below the photoelectric conversion element in this embodiment, the electrodes used in the photoelectric conversion element preferably have a visible light and infrared light transmittance of 90% or more, and more preferably 95% or more.

[0067] As an electrode material that satisfies these conditions, a transparent conducting oxide (TCO) that has high transmittance to visible light and infrared light and low resistance is preferable. Although a thin metal film such as gold can be used as an electrode, the resistance increases drastically when the transmittance is increased to 90% or more. Therefore, a TCO is preferable as an electrode. As a TCO, ITO, IZO, AZO, FTO, SnO2, TiO2 and ZnO2 are particularly preferable.

[0068] The method of forming the electrode is not particularly limited, and can be appropriately selected in consideration of the suitability with the electrode material. When a transparent electrode is used, the method of forming the electrode can be specifically a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method or an ion plating method, or a chemical method such as a CVD or a plasma CVD method. When the material of the electrode is a transparent conductive metal oxide such as ITO, the method of forming the electrode can be, for example, an electron beam method, a sputtering method, a resistance heating deposition method, a chemical reaction method (for example, a sol-gel method, etc.), or a method of applying a dispersion of the metal oxide. Furthermore, a film of a transparent conductive metal oxide such as ITO can be subjected to UV-ozone treatment and plasma treatment.

[0069] The photoelectric conversion film 110 may include the photoelectric conversion element material of this embodiment, or may include the above organic thin film. More specifically, for example, the photoelectric conversion film 110 includes a photoelectric conversion layer 104, a first auxiliary layer 103 located on the lower electrode film 102 side of the photoelectric conversion layer 104, and a second auxiliary layer 105 located on the upper electrode film 106 side of the photoelectric conversion layer 104. Note that the photoelectric conversion film 110 shown in FIG. 1 includes the first auxiliary layer 103 and the second auxiliary layer 105, but the photoelectric conversion film may include only one of these auxiliary layers. Alternatively, the photoelectric conversion film may include only the photoelectric conversion layer 104 without including any auxiliary layer. When the photoelectric conversion film does not include an auxiliary layer, the photoelectric conversion layer 104 is the above organic thin film, and when the photoelectric conversion film includes an auxiliary layer, at least one of the photoelectric conversion layer 104 and the auxiliary layer is the above organic thin film. However, from the viewpoint of more effectively and reliably achieving the effects of the present invention, the auxiliary layer is preferably the above-described organic thin film containing the material for photoelectric conversion elements of this embodiment.

[0070] The photoelectric conversion layer 104 may be an organic semiconductor film generally used as a photoelectric conversion layer, or may be the above-mentioned organic thin film. In the photoelectric conversion layer 110, the organic semiconductor film and the organic thin film may be one layer or multiple layers. When it is one layer, a p-type organic semiconductor film, an n-type organic semiconductor film, or a mixed film thereof (hereinafter, may be a "bulk heterostructure") is used. On the other hand, when it is multiple layers, the number of layers may be about 2 to 10 layers, and it has a structure in which any of a p-type organic semiconductor film, an n-type organic semiconductor film, or a mixed film thereof (hereinafter, may be a "bulk heterostructure") is laminated, and a buffer layer may be inserted between the layers.

[0071] The photoelectric conversion layer 104 in this embodiment may or may not contain the material for photoelectric conversion element of this embodiment, and may contain a material other than the material for photoelectric conversion element of this embodiment. Among them, the photoelectric conversion layer 104 preferably contains at least one of an organic p-type semiconductor, an organic n-type semiconductor, and a light absorbing material, since incident light energy of a desired wavelength can be converted into an electric signal more efficiently. Among them, it is preferable that the organic p-type semiconductor is one that easily donates electrons (i.e., has a small ionization potential) to the light absorbing material, or that the organic n-type semiconductor is one that easily accepts electrons (i.e., has a large electron affinity) to the light absorbing material, since incident light energy can be converted into an electric signal more efficiently. Here, the ionization potential (HOMO level) refers to a value measured by photoelectron yield spectroscopy or photoelectron spectroscopy. In addition, the electron affinity (LUMO level) refers to a value obtained by calculating an energy band gap value from the longest wavelength absorption edge of the near-infrared spectroscopy spectrum and subtracting it from the above-mentioned HOMO level, or a value measured by inverse photoelectron spectroscopy.

[0072] When an organic semiconductor film is used, the film may be one layer or two or more layers. The organic semiconductor film may be an organic p-type semiconductor film, an organic n-type semiconductor film, a light absorbing material film, or a mixed film thereof (bulk heterostructure). In particular, the organic semiconductor film preferably has a bulk heterojunction structure layer. In this case, by incorporating a bulk heterojunction structure into the photoelectric conversion film, the drawback of the short carrier diffusion length of the photoelectric conversion film can be compensated for, and the photoelectric conversion efficiency can be improved.

[0073] The thickness of the photoelectric conversion layer 104 may be, for example, 0.5 nm or more and 5000 nm or less, 1 nm or more and 1000 nm or less, or 5 nm or more and 500 nm or less.

[0074] The organic semiconductor will be described in detail below.

[0075] An organic p-type semiconductor is a donor organic semiconductor (hereinafter also referred to as a "donor organic compound"), and is mainly represented by a hole-transporting organic compound, and refers to an organic compound that has the property of easily donating electrons. More specifically, it refers to the organic compound that has the smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound that has electron-donating properties can be used as a donor organic compound.

[0076] Examples of such donor organic compounds include triarylamine compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, cyanine compounds, merocyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, condensed aromatic carbon ring compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), and metal complexes having nitrogen-containing heterocyclic compounds as ligands. It should be noted that, without being limited to these, as described above, any organic compound having a smaller ionization potential than the organic compound used as the acceptor organic compound can be used as the donor organic semiconductor.

[0077] An organic n-type semiconductor is an acceptor organic semiconductor (hereinafter also referred to as an "acceptor organic compound"), and is mainly represented by an electron transporting organic compound, and refers to an organic compound that has the property of easily accepting electrons. More specifically, when two organic compounds are used in contact with each other, it refers to the organic compound that has a larger electron affinity. Therefore, any organic compound that has electron accepting properties can be used as an acceptor organic compound.

[0078] Examples of such an acceptor organic compound include condensed aromatic carbocyclic compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives, and fullerene derivatives), 5- to 7-membered heterocyclic compounds containing a nitrogen atom, an oxygen atom, or a sulfur atom (e.g., pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, Examples of the metal complexes include pyrazole, imidazole, thiazole, oxazole, indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, triazolopyrimidine, tetrazaindene, oxadiazole, imidazopyridine, pyrazine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, and tribenzazepine), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, and nitrogen-containing heterocyclic compounds as ligands. In addition, the metal complexes are not limited to these, and as described above, any organic compound having a larger electron affinity than the organic compound used as the donor organic compound can be used as the acceptor organic semiconductor.

[0079] The light absorbing material is a compound having a maximum light absorption wavelength in the visible light region, particularly in the range of 450 nm to 650 nm. The absorption intensity of the light absorbing material at the maximum light absorption wavelength is preferably greater than the absorption intensity of the donor organic compound or the acceptor organic compound at the maximum light absorption wavelength. By having such an absorption intensity, the light absorbing material can selectively absorb incident light at the maximum light absorption wavelength. After the incident light is absorbed by the light absorbing material and the photons become excitons, exciton separation occurs at the interface between the donor organic compound and the acceptor organic compound, and hole and electron carriers can be efficiently generated.

[0080] As such a light absorbing material, a compound generally called a dye can be used. For example, a phthalocyanine derivative, a subphthalocyanine derivative, a quinacridone derivative, a porphyrin derivative, a naphthalene or perylene derivative, a phthaloperylene derivative, a styryl derivative, a cyanine derivative, a hemicyanine derivative, a merocyanine derivative, a rhodacyanine derivative, an oxonol derivative, a hemioxonol derivative, a croconium derivative, a squarylium derivative, an azamethine derivative, an arylidene derivative, an azo derivative, an azomethine derivative, a metallocene derivative, a fulgide derivative, a phenazine derivative, a phenothiazine derivative, a polyene derivative, an acridine derivative, an acridinone derivative, a diphenylamine derivative, a triarylamine derivative such as triphenylamine, naphthylamine, and styrylamine, a quinophthalone derivative, a phenoxazine derivative, a chlorophyll derivative, a rhodamine derivative, a diphenylmethane or triphenylmethane derivative, a xanthene derivative, an acridine derivative, a phenoxazine derivative, a quinoline derivative, an oxazine derivatives, thiazine derivatives, quinone derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, indigo or thioindigo derivatives, pyrrole derivatives, pyridine derivatives, dipyrrine derivatives, indole derivatives, diketopyrrolopyrrole derivatives, coumarin derivatives, fluorene derivatives, fluorenone derivatives, fluoranthene derivatives, anthracene derivatives, pyrene derivatives, carbazole derivatives, phenylenediamine derivatives, benzidine derivatives, phenanthroline derivatives, imidazole derivatives, oxazoline derivatives, thiazoline derivatives, triazole derivatives, thiadiazole derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiophene derivatives, selenophene derivatives, silole derivatives, germole derivatives, stilbene derivatives, phenylenevinylene derivatives, pentacene derivatives, rubrene derivatives, thienothiophene derivatives, benzodithiophene derivatives, xanthenoxanthene derivatives, and fullerene derivatives. However, without being limited to these, as described above, any compound having an absorption intensity greater than the absorption intensity at the maximum light absorption wavelength of the donor organic compound or the acceptor organic compound can be used as the light absorbing material.The light absorbing material can also function as a donor organic compound or an acceptor organic compound.

[0081] The first auxiliary layer 103 includes, for example, at least one of a hole blocking layer and an electron transport layer. When the first auxiliary layer 103 includes two of them, the electron transport layer and the hole blocking layer are usually laminated in this order from the photoelectric conversion layer 104 side. The electron transport layer transports electrons generated in the photoelectric conversion layer 104 to the first electrode 102, and blocks holes from moving from the first electrode 102 to the photoelectric conversion layer 104. The hole blocking layer prevents holes from moving from the first electrode 102 to the photoelectric conversion layer 104, prevents recombination in the photoelectric conversion layer 104, reduces dark current, reduces noise, and expands the dynamic range. In addition, one layer may have the functions of both the hole blocking layer and the electron transport layer.

[0082] The second auxiliary layer 105 includes, for example, at least one of an electron blocking layer and a hole transport layer. When the second auxiliary layer 105 includes two of them, the hole transport layer and the electron blocking layer are usually laminated in this order from the photoelectric conversion layer 104 side. The hole transport layer transports generated holes from the photoelectric conversion layer 104 to the second electrode 106, and blocks the movement of electrons from the second electrode 106 to the photoelectric conversion layer 104. The electron blocking layer prevents the movement of electrons from the second electrode 106 to the photoelectric conversion layer 104, prevents recombination in the photoelectric conversion layer 104, reduces dark current, and reduces noise to expand the dynamic range. In addition, one layer may have the functions of both the electron blocking layer and the hole transport layer.

[0083] The photoelectric conversion element material of this embodiment may be included in either the first auxiliary layer 103 or the second auxiliary layer 105, but is preferably included in the first auxiliary layer 103. In the photoelectric conversion element of this embodiment, it is preferable that the first auxiliary layer 103 of the first auxiliary layer 103 and the second auxiliary layer 105 includes the above organic thin film. In addition, it is more preferable that the photoelectric conversion element material of this embodiment is included in at least one of the hole blocking layer and the electron transport layer in the first auxiliary layer 103. In the photoelectric conversion element of this embodiment, it is preferable that at least one of the hole blocking layer and the electron transport layer is the above organic thin film. This makes it possible to more effectively and reliably achieve the effects of the present invention.

[0084] Materials other than the material for a photoelectric conversion element of this embodiment that may be contained in each layer of the auxiliary layer will be described below.

[0085] The material for the hole transport layer is not particularly limited as long as it is known as a hole transport layer in a photoelectric conversion element such as a solid-state imaging element. Examples of the material include polyaniline and a doped material thereof, and the cyanide compounds described in WO 2006 / 019270.

[0086] More specifically, materials constituting the hole transport layer include selenium, iodides such as copper iodide (CuI), cobalt complexes such as layered cobalt oxides, CuSCN, molybdenum oxide (MoO3, etc.), nickel oxide (NiO, etc.), 4CuBr·3S (C4H9), and organic hole transport materials. Among these, an example of an iodide is copper iodide (CuI). An example of a layered cobalt oxide is AxCoO2 (wherein A represents Li, Na, K, Ca, Sr, or Ba, and 0≦X≦1). Examples of organic hole transport materials include polythiophene derivatives such as poly-3-hexylthiophene (P3HT), poly(3,4-ethylenedioxythiophene), (PEDOT; for example, product name "Baytron P" manufactured by Starck V Tech), fluorene derivatives such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeO-TAD), carbazole derivatives such as polyvinylcarbazole, triphenylamine derivatives, diphenylamine derivatives, polysilane derivatives, and polyaniline derivatives. Further, examples of materials for the hole transport layer include compound semiconductors having monovalent copper, such as CuInSe2 and copper sulfide (CuS), gallium phosphide (GaP), nickel oxide (NiO), cobalt oxide (CoO), iron oxide (FeO), bismuth oxide (Bi2O3), molybdenum oxide (MoO2), and chromium oxide (Cr2O3).

[0087] In addition, if the hole transport layer has a LUMO level higher than that of the photoelectric conversion film, it is preferable because it has a rectification effect that suppresses the movement of electrons generated in the photoelectric conversion film to the electrode side, and thus has an electron blocking function. Such a hole transport layer is also called an electron blocking layer.

[0088] Among the materials constituting the electron blocking layer, examples of low molecular weight organic compounds include aromatic diamine compounds such as N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) and 4,4'-bis[N-(naphthyl)-N-phenyl-amino]biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivatives, pyrazoline derivatives, tetrahydroimidazole, polyarylalkanes, butadiene, and the like. Dienes, 4,4',4" tris(N-(3-methylphenyl)N-phenylamino)triphenylamine (m-MTDATA), porphyrins, tetraphenylporphyrin copper, phthalocyanines, porphyrin compounds such as copper phthalocyanine and titanium phthalocyanine oxide, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted Examples of the organic compounds of high molecular weight include, for example, polymers such as phenylenevinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, and their derivatives. Any compound having sufficient hole transport properties can be used as a material constituting the electron blocking layer, even if it is not an electron donating compound. Furthermore, examples of inorganic compounds constituting the electron blocking layer include metal oxides such as calcium oxide, chromium oxide, chromium copper oxide, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, strontium copper oxide, niobium oxide, molybdenum oxide, indium copper oxide, indium silver oxide, and iridium oxide, selenium, tellurium, and antimony sulfide. These compounds are used alone or in combination of two or more.

[0089] From the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency, the thickness of the hole transport layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and even more preferably 50 nm or more and 200 nm or less.

[0090] The hole transport layer and the electron blocking layer may be formed by a conventional method, and may be a dry film-forming method such as a vacuum deposition method, or a wet film-forming method such as a solution coating method. However, from the viewpoint of leveling the coating surface, a wet film-forming method is preferable. Examples of the dry film-forming method include a vapor deposition method such as a vacuum deposition method, and a sputtering method. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum deposition is preferable. Examples of the wet film-forming method include an inkjet method, a spray method, a nozzle print method, a spin coat method, a dip coat method, a cast method, a die coat method, a roll coat method, a bar coat method, and a gravure coat method.

[0091] The material constituting the electron transport layer is not particularly limited as long as it is known as an electron transport layer in a photoelectric conversion element such as a solid-state imaging element, and examples thereof include organic compounds such as octaazaporphyrin, perfluorinated bodies of p-type semiconductors (e.g., perfluoropentacene and perfluorophthalocyanine), fullerene, fullerene derivatives (e.g., [6,6]-phenyl-C61-butylic acid methyl ester; PCBM), perylene, indenoindene and indenoindene derivatives, and inorganic oxides such as titanium oxide (TiO2, etc.), nickel oxide (NiO), tin oxide (SnO2), tungsten oxide (WO2, WO3, W2O3, etc.), zinc oxide (ZnO), niobium oxide (Nb2O5, etc.), tantalum oxide (Ta2O5, etc.), yttrium oxide (Y2O3, etc.), and strontium titanate (SrTiO3, etc.). The electron transport layer may be porous or dense, and when they are laminated, it is preferable that the porous electron transport layer and the dense electron transport layer are laminated in this order from the photoelectric conversion film side.

[0092] In addition, if the electron transport layer has a HOMO level lower than that of the photoelectric conversion film, it is preferable because it has a hole blocking function that has a rectification effect that suppresses the movement of holes generated in the photoelectric conversion film to the counter electrode side. Such an electron transport layer is also called a hole blocking layer.

[0093] Examples of materials constituting the hole blocking layer include oxadiazole derivatives such as 1,3-bis(4-tert-butylphenyl-1,3,4-oxadiazolyl)phenylene (OXD-7), anthraquinodimethane derivatives, diphenylquinone derivatives, bathocuproine, bathophenanthroline, and derivatives thereof, triazine compounds, triazole compounds, tris(8-hydroxyquinolinato)aluminum complexes, bis(4-methyl-8-quinolinato)aluminum complexes, silole compounds, and porphyrins. Examples of the semiconductor material include n-type inorganic oxides such as titanium oxide, zinc oxide, and gallium oxide, and alkali metal fluorides such as lithium fluoride, sodium fluoride, and cesium fluoride. Furthermore, organic semiconductor molecules doped with alkali metal compounds are also preferred because they have the function of improving electrical connection with the counter electrode. These are used alone or in combination of two or more.

[0094] From the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency, the thickness of the electron transport layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and even more preferably 50 nm or more and 200 nm or less.

[0095] The method for forming the electron transport layer and the hole blocking layer may be a conventional method, and may be either a dry film-forming method such as a vacuum deposition method or a wet film-forming method such as a solution coating method, but from the viewpoint of leveling the coating surface, a wet film-forming method is preferred. Examples of the dry film-forming method include a vapor deposition method such as a vacuum deposition method and a sputtering method. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum deposition is preferred. Examples of the wet film-forming method include an inkjet method, a spray method, a nozzle print method, a spin coat method, a dip coat method, a cast method, a die coat method, a roll coat method, a bar coat method, and a gravure coat method.

[0096] The photoelectric conversion element of this embodiment may include a single layer or two or more layers of auxiliary layers other than the first auxiliary layer 103 between the first auxiliary layer 103 and the lower electrode 102. Examples of such auxiliary layers include a hole injection layer that improves hole injection from the lower electrode 102 to the first auxiliary layer 103. Examples of materials constituting the hole injection layer include polymeric materials such as phthalocyanine derivatives, starburst amines such as m-MTDATA (4,4',4''-tris[phenyl(m-tolyl)amino]triphenylamine), polythiophenes such as PEDOT (poly(3,4-ethylenedioxythiophene)), and polyvinylcarbazole derivatives. The thickness of this auxiliary layer may be the same as that of the first auxiliary layer 103.

[0097] The photoelectric conversion element of this embodiment may include a single layer or two or more layers of an auxiliary layer other than the second auxiliary layer 105 between the second auxiliary layer 105 and the upper electrode 106. Examples of such an auxiliary layer include an electron injection layer that improves the electron injection from the upper electrode 106 to the second auxiliary layer 105, and an electron transport layer. Examples of materials constituting the electron injection layer include metals such as cesium, lithium, and strontium, and lithium fluoride. Materials constituting the electron transport layer may be the same as those described above. In addition, the thickness of this auxiliary layer may be the same as that of the second auxiliary layer 105.

[0098] The photoelectric conversion element of this embodiment may include, in addition to the above-mentioned layers, at least one of an interlayer contact improving layer and a crystallization prevention layer located between these layers.

[0099] The interlayer contact improving layer serves to reduce damage to the film immediately below the upper electrode 106, for example the photoelectric conversion film 110, during the deposition of the upper electrode 106. In particular, high energy particles present in the device used for depositing the upper electrode 106, for example sputtering particles, secondary electrons, Ar particles, negative oxygen ions, etc., collide with the film immediately below, causing deterioration in quality and performance degradation such as an increase in leakage current and a decrease in sensitivity. As one method for preventing this, it is preferable to provide an interlayer contact improving layer on the upper layer of the film immediately below. As the material for the interlayer contact improving layer, organic substances such as copper phthalocyanine, NTCDA, PTCDA, [dipyrazino[2,3-F:2',3'-H]quinoxaline-2,3,6,7,10,11-hexacarbonitrile] (HATCN), acetylacetonate complex, BCP, organic-metal compounds, and inorganic substances such as MgAg and MgO are preferably used. The appropriate range of the thickness of the interlayer contact improving layer varies depending on the configuration of the photoelectric conversion film, the film thickness of the electrode, etc., but it is preferable that the thickness be 2 nm or more and 500 nm or less, particularly from the viewpoint of selecting a material that does not absorb in the visible range or using a thin thickness.

[0100] As described above, the photoelectric conversion element of this embodiment is connected to the storage section, which is a capacitor for storing the generated electric charge, and the readout section, which is a transistor circuit for reading out, via a connection section made of a conductive material. In addition, the photoelectric conversion element may include a protective structure from the outside air, such as a protective film, a substrate for maintaining strength, a microlens for collecting light, etc., as necessary.

[0101] The readout section is provided to read out a signal corresponding to the charge generated in the photoelectric conversion film. The readout section is composed of, for example, a CCD, a CMOS circuit, or a TFT circuit, and is preferably shielded from light by a light-shielding layer disposed in the insulating layer. The readout circuit is electrically connected to the corresponding electrode via a connection section. In addition, in order to secure the amount of charge required for reading, a storage section composed of a capacitor or the like may be interposed between the electrode and the connection section. The connection section is embedded in the insulating layer and is a plug or the like for electrically connecting the electrode (for example, a transparent electrode or a counter electrode) and the readout section. When the member thus configured is a solid-state imaging element, when light is incident, the light is incident on the photoelectric conversion film, where a charge is generated. Electrons of the generated charge are collected (and stored) by one electrode, and holes are collected by the other electrode. A voltage signal corresponding to the amount is output by the readout section to the outside of the solid-state imaging element.

[0102] (Image sensor) The imaging element of this embodiment may be the same as a conventional imaging element in other configurations as long as it includes the photoelectric conversion element of this embodiment. For example, the imaging element of this embodiment includes a large number of photoelectric conversion elements of this embodiment arranged in an array. That is, by arranging a large number of photoelectric conversion elements in an array, a solid-state imaging element is formed that indicates not only the amount of incident light but also incident position information.

[0103] The imaging element of this embodiment may include one photoelectric conversion element of this embodiment, or may include two or more stacked elements. When two or more photoelectric conversion elements of this embodiment are stacked, each photoelectric conversion element may selectively detect light of different wavelength bands and perform photoelectric conversion. For example, when three or more photoelectric conversion elements of this embodiment are stacked, at least one may acquire a green color signal, at least one may acquire a blue color signal, at least one may acquire a red color signal, and at least one may acquire an infrared color signal. This allows the imaging element to acquire multiple types of color signals in one pixel without using a color filter. In addition, color signals other than the color signals detected by the photoelectric conversion element of this embodiment may be sensed by a device having a conventionally known silicon photodiode.

[0104] In an imaging element, if a photoelectric conversion element arranged closer to the light source does not block (i.e., transmits) the absorption wavelengths of another photoelectric conversion element arranged behind it when viewed from the light source side, devices having multiple photoelectric conversion elements and silicon photodiodes may be stacked.

[0105] In the imaging element, from the viewpoint of ease of molding, the photoelectric conversion elements may be partially configured as thin films on the same plane with no structural separation between adjacent photoelectric conversion elements.

[0106] The imaging element of the present embodiment may further include a substrate. The substrate is used to manufacture the imaging element by stacking each layer thereon, or to increase the mechanical strength of the imaging element. The type of substrate is not particularly limited, and examples thereof include a semiconductor substrate, a glass substrate, and a plastic substrate.

[0107] (Light sensor) The optical sensor of this embodiment may be configured similarly to a conventional optical sensor as long as it includes the image sensor of this embodiment. This optical sensor receives light at the image sensor of this embodiment and outputs an electrical signal according to the amount of received light.

[0108] (Solid-state imaging device) The solid-state imaging device of this embodiment may be a CMOS image sensor, and may have a pixel section as an imaging area on a semiconductor substrate, and may further have a peripheral circuit section having a row scanning section, a horizontal selection section, a column scanning section, and a system control section in a peripheral region or vertically below the pixel section. The pixel section has the imaging element of this embodiment.

[0109] The photoelectric conversion element of this embodiment has the following advantages by using the material for photoelectric conversion elements of this embodiment. That is, the photoelectric conversion element of this embodiment is less likely to short circuit or have pinholes, so the dark current value is low. As a result, the photoelectric conversion element of this embodiment has excellent leak prevention properties (particularly in the dark). Furthermore, the photoelectric conversion element of this embodiment tends to have a high light-dark ratio, and in that case, has even better leak prevention properties. In addition, the photoelectric conversion element of this embodiment has excellent transport properties for holes and electrons, even though the material for photoelectric conversion elements is less likely to aggregate, so that the photoelectric conversion efficiency is high. Furthermore, the photoelectric conversion element of this embodiment has good heat resistance by using the material for photoelectric conversion elements of this embodiment, and durability in the manufacturing process and in practical environments is improved. EXAMPLES

[0110] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The synthesized compounds were further purified by sublimation as necessary.

[0111] <Synthesis Example 1> [ka]

[0112] A mixture of 1.5 g of 2,6-dibromonaphthalene-1,4,5,8-tetracarboxylic dianhydride (Tokyo Chemical Industry Co., Ltd.), 1.0 g of 4-cyanophenol (Tokyo Chemical Industry Co., Ltd.), and 7 mL of isoquinoline (Tokyo Chemical Industry Co., Ltd.) was stirred at 180° C. for 5 hours. After cooling to room temperature, methanol was added and the precipitated mixture was filtered. Compound (2) was obtained by washing with methanol.

[0113] [ka] 1.0 g of compound (2) and 0.5 g (2.1 molar equivalents relative to compound (2)) of 4-aminobenzonitrile (Tokyo Chemical Industry Co., Ltd.) were added to 10 mL of acetic acid (Tokyo Chemical Industry Co., Ltd.), and the resulting mixture was stirred at 125° C. for 8 hours. After that, it was cooled to room temperature, methanol was added, and the precipitated mixture was filtered. It was further washed with methanol to obtain compound (3). The results of NMR measurement are shown below. 1 HNMR(500MHz,DMSO-d6):8.35(s,2H),8.02(d,4H),7.91(d,4H),7.63(d,4H),7.21(d,4H)

[0114] <Synthesis Example 2> [ka]

[0115] Compound (4) was obtained in the same manner as in Synthesis Example 1, except that m-cresol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of 4-cyanophenol. The results of NMR measurement thereof are shown below. 1 HNMR(500MHz,DMSO-d6):8.06(s,2H),8.02(d,4H),7.65(d,4H),7.37(m,1H),7.11(d,1H),7.00(s,1H),6.96(dd,1H),2.32(s,6H)

[0116] <Synthesis Example 3> [ka]

[0117] 2.0 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride (hereinafter referred to as "compound (5)" (manufactured by Tokyo Chemical Industry Co., Ltd.)) and 1.5 g of aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.2 molar equivalents relative to compound (5)) were added to 15 mL of acetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and the resulting mixture was stirred at 125°C reflux for 8 hours. Thereafter, it was cooled to room temperature, methanol was added thereto, and the precipitated mixture was filtered. After further washing with methanol, pyridine was added and stirred for 5 minutes. Next, after filtration and washing with methanol, a white solid compound (6) was obtained through sublimation purification. The results of NMR measurement are shown below. 1 HNMR(500MHz,DMSO-d6):8.73(s,4H),7.58~7.45(m,10H)

[0118] <Synthesis Example 4> [ka]

[0119] 6.0 g of compound (5), 6.1 g of isoquinoline (Tokyo Chemical Industry Co., Ltd.) (2.1 molar equivalents relative to compound (5)), and 6.6 g of 4-aminobenzonitrile (Tokyo Chemical Industry Co., Ltd.) (2.5 molar equivalents relative to compound (5)) were added to 90 mL of m-cresol (Tokyo Chemical Industry Co., Ltd.), and the resulting mixture was stirred at 180° C. for 8 hours. After that, it was cooled to room temperature, methanol was added thereto, and the precipitate was filtered. After washing with methanol, an aqueous potassium carbonate solution was added and stirred for 5 minutes. Next, after filtration, it was washed with water and methanol, and purified by sublimation to obtain compound (7) as a white solid. The results of the NMR measurement are shown below. 1HNMR(500MHz,HFIP-d2):8.93(s,4H),8.77(dm,4H),7.55(dm,4H)

[0120] [Evaluation of compound crystallinity] The crystallinity of the synthesized compounds was evaluated. A desktop X-ray diffractometer (Rigaku Corporation, product name: MiniFlex600) was used for the crystallinity evaluation. The X-ray source was CuKα, and the maximum X-ray diffraction (XRD) peak intensity was measured from the spectrum obtained at a scan rate of 20° / min. The results are shown in Table 1. The maximum peak intensity is shown as a relative value when the value of compound (4) is set to 1.

[0121] [Preparation and evaluation of organic thin films and photoelectric conversion devices] In the following examples and comparative examples, the organic thin film and the photoelectric conversion element were prepared using a deposition machine, and measurements were performed under atmospheric conditions of current and voltage application. The prepared photoelectric conversion element was placed in a measurement chamber, and measurements were performed under current and voltage application. A semiconductor parameter analyzer (manufactured by Keithley) was used for the current and voltage application measurements. Irradiation of the irradiated light was performed using a light source device (manufactured by Asahi Spectroscopy, product name (PVL-3300)) under conditions of an irradiated light wavelength of 550 nm and an irradiated light half-width of 20 nm. The light-dark ratio is the current value when irradiated with light divided by the current value in a dark place.

[0122] Example 1 On an ITO transparent conductive glass (ITO manufactured by Geomatec Co., Ltd., thickness 100 nm), boron subphthalocyanine chloride (purified product manufactured by Sigma-Aldrich, purity >99%, LUMO: -2.6 eV, energy level difference: 2.7 eV) was vacuum-formed to a thickness of 100 nm as a photoelectric conversion layer, and a sublimation refined product of tris(8-quinolinolato)aluminum (Alq3) (manufactured by Tokyo Chemical Industry Co., Ltd.) was formed on the layer to a thickness of 25 nm as auxiliary layer 1 by resistance heating vacuum deposition. Next, compound (3) was formed as auxiliary layer 2 to a thickness of 25 nm by resistance heating vacuum deposition. Next, aluminum was vacuum-formed to a thickness of 100 nm on the auxiliary layer 2 as an electrode, to obtain a photoelectric conversion element. For the obtained photoelectric conversion element, a voltage of 5 V was applied using ITO and aluminum as electrodes, and the current value in a dark place and the current value when irradiated with light were measured. The light / dark ratio was calculated from the measurement results. The results are shown in Table 1. The dark current value is shown as a relative value when the value in Comparative Example 1 described later is set to 1.

[0123] Example 2 A single-layer organic thin film and an electric conversion element were prepared in the same manner as in Example 1, except that compound (4) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0124] Comparative Example 1 A single-layer organic thin film and an electric conversion element were prepared in the same manner as in Example 1, except that compound (5) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0125] Comparative Example 2 A single-layer organic thin film and an electric conversion element were prepared in the same manner as in Example 1, except that compound (6) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0126] Comparative Example 3 A single-layer organic thin film and an electric conversion element were prepared in the same manner as in Example 1, except that compound (7) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0127] [Table 1]

[0128] From the results shown in Table 1, it was found that the photoelectric conversion element of the present invention has excellent leak prevention properties (particularly in the dark) since it shows a low dark current value. In particular, in Example 1, it was found that the XRD maximum peak intensity was small, so that it had low crystallinity, a low LUMO, and a large difference in energy levels, so that it showed a high light-dark ratio and had better leak prevention properties. From the above, it was found that the compound of the present invention is suitable as a material for a photoelectric conversion element, particularly as a material contained in the electron transport layer and hole blocking layer of a photoelectric conversion element. [Industrial Applicability]

[0129] By using a photoelectric conversion element material containing the compound (1) of the present invention, a photoelectric conversion element excellent in required properties such as hole or electron leakage prevention and transport properties, heat resistance, visible light transparency, etc. can be provided. Therefore, the compound (1), photoelectric conversion element material, organic thin film, and photoelectric conversion element of the present invention have industrial applicability in fields where such properties are required. Specifically, as a solid-state imaging element, the imaging element in a security camera, an in-vehicle camera, an unmanned aerial vehicle camera, an agricultural camera, an industrial camera, a medical camera such as an endoscope camera, a game machine camera, a digital still camera, a digital video camera, a mobile phone camera, and a camera for a mobile device other than the above; an image reading element in a facsimile, a scanner, a copy machine, etc.; and an optical sensor in a bio- and chemical sensor, etc. Also, as a display using electroluminescence, the industrial applicability is in television monitors, touch monitors, digital signage, wearable displays, electronic paper, head-up displays for mobility applications, etc.

[0130] This application is based on a Japanese patent application (Patent Application No. 2023-069028) filed on April 20, 2023, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0131] 100...photoelectric conversion element, 101...substrate, 102...lower electrode, 103...first auxiliary layer, 104...photoelectric conversion layer, 105...second auxiliary layer, 106...upper electrode, 110...photoelectric conversion film.

Claims

1. The following formula (1): 【Chemistry 1】 (X is an oxygen atom or NR ６ and R １ , R ２ , R ３ , R ４ , R ５ and R ６ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxy group, a thiol group, an amino group, a cyano group, a carboxy group, a nitro group, and an optionally substituted linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, a carboalkoxy group, a carboaryloxy group, an acyl group, and a monovalent heterocyclic group, and any adjacent R １ , R ２ , R ３ , R ４ , R ５ and R ６ may be part of a fused aliphatic ring or a fused aromatic ring. １ , R ２ , R ３ , R ４ , R ５ and X may be the same or different. The condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon. An organic thin film comprising a compound represented by the formula:

2. 2. The organic thin film according to claim 1, wherein the energy level of the lowest unoccupied molecular orbital of the compound represented by formula (1) obtained by density functional theory is −6.00 eV or more and −3.40 eV or less.

3. 2. The organic thin film according to claim 1, wherein the difference between the energy level of the lowest unoccupied molecular orbital and the energy level of the highest occupied molecular orbital of the compound represented by formula (1) obtained by a density functional theory is 3.00 eV or more and 4.00 eV or less.

4. The organic thin film according to claim 1, wherein the compound represented by formula (1) is a material for a photoelectric conversion element.

5. 2. The organic thin film according to claim 1, which has a maximum absorption wavelength in its light absorption band of 450 nm or less.

6. A photoelectric conversion element including a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film, A photoelectric conversion element, wherein the photoelectric conversion film comprises the organic thin film according to claim 1 .

7. The photoelectric conversion film includes a photoelectric conversion layer and an auxiliary layer, The photoelectric conversion element according to claim 6 , wherein the auxiliary layer is made of only the organic thin film or is made of a plurality of films including the organic thin film.

8. An imaging device comprising the photoelectric conversion element according to claim 6 or 7.

9. The imaging element according to claim 8 , wherein two or more of the photoelectric conversion elements are stacked.

10. An imaging device comprising a plurality of photoelectric conversion elements according to claim 6 or 7 arranged in an array.

11. An optical sensor comprising the imaging element according to claim 8.

12. A solid-state imaging device comprising the imaging element according to claim 8 .

Images